Origin: Puerto Rico
Story: When you go to sleep, the sandman comes into your dreams. He makes sure that you fall fast asleep.
Meaning: he is the one who helps you stay asleep.
Usage: Usually parents say it to their child when they want her to go to sleep. They’ll say, “If you don’t go to bed soon, the Sandman will miss you.” Also adults say it when they are ready to go to sleep. “I’m going to go see the Sandman”.
Analysis: This is an almost folktale creature in its conception, yet mentioning the Sandman usually seems to just be folk speech. While children might conceptualize him as an actual being, it seems that adults use it primarily as a form of expression or euphemism. His usage creates a calm and non-frightening incentive for children to go to sleep, which is probably the only effective way to make them sleep: it would be rather hard to frighten them into obedience with the boogeyman in this case, as they would never go to sleep. Presenting him as someone you would meet in your dreams, therefore, someone benevolent, is probably the best approach parents can make.